Spirocyclic C-glycosides represent a key structural component of papulacandin compounds and related analogs. Papulacandins are secondary metabolites obtained by the cultivation of a specific strain of Papularia sphaerosperma (NRRL 8086) and consist of two primary components A and B in addition to three subsidiary components C, D and E. The papulacandin natural products and related analogs have received attention over the past couple of decades because of their antifungal activity (see e.g., U.S. Pat. Nos. 4,278,665 and 5,091,413; and Traxler, P., et al., "Papulacandins, A New Family of Antibiotics with Antifungal Activity/Structures of Papulacandins A, B, C and D" J. Antibiotics, XXXIII(9), 967-978 (1980).) and antipneumocystis activity (see e.g., U.S. Pat. No. 5,089,478). Other compounds related to the papulacandin family where the spiro ring has opened are also known, i.e., chaetiachandin (see Komori, T., et al., "Chaetiacandin, A Novel Papulacandin II. Structure Determination" J. Antibiotics, XXXVIII(4), 544-546 (1995).) and fusacandins. The fusacandins have been reported as having antifungal activity (see e.g., U.S. Pat. Nos. 5,773,421 and 5,585,251; and Hochlowski, J. E., et al. "Fusacandins A and B; Novel Antifungal Antibiotics of the Papulacandin Class from Fusarium sambucinum II. Isolation and Structural Elucidation," J. of Antibiotics, 48(7), 614-618 (1995).)
Current studies of papulacandin compounds and their analogs have resulted primarily from isolation and modification of the natural products; therefore, derivatization of the compounds is limited. Consequently, there is a need for an efficient means for making key intermediates which provide more flexibility in evaluating potential pharmaceutically active materials that either contain or are derived from spirocyclic C-glycosides.